1. Field of the Invention
The present invention relates to an ink sheet cassette capable of changing paths of an ink sheet from one to another to record a desired image depending on the property of the ink sheet. The present invention also concerns an image recording apparatus using such an ink sheet cassette.
The image recording apparatus described herein includes printers, word processors, typewriters, facsimiles and so on. The ink sheet described herein includes various types of ink sheets such as a ribbon-like ink sheet having a relatively small width which can be used in the so-called serial type recording system and an ink sheet having substantially the same width as that of a recording sheet used, which can be used in the so-called full-line type recording system. Ink sheets used in the present invention may have different properties.
2. Related Background Art
Recently, the thermal transfer type of recording system has been developed and it is currently used as an information processing system. The thermal transfer type of recording system generally uses a thermal transfer medium comprising a ribbon-like substrate and a thermally transferable ink applied to the substrate, the ink including a colorant which is dispersed in a hot-melt binder. The thermal transfer medium is superposed on a recording sheet with the thermally transferable ink layer thereof contacting the recording sheet. Heat is then applied to the thermal transfer medium from a thermal head through the substrate to fuse the ink. The fused ink is transferred to the recording sheet to form an image corresponding to the configuration of heat transfer on the recording sheet. The thermal transfer type recording system can use paper as the recording sheet while maintaining advantages in the heat sensitive recording process. It also can eliminate problems associated with the use of heat sensitive recording sheets.
However, the thermal transfer type recording method has some problems with respect to its properties of transfer. For example, the quality of print is highly influenced by the smoothness of the surface of the recording sheet used. If a recording sheet having a smoother surface is used, the quality of print is increased. If not so, the quality of print is very much degraded. The most typical recording sheet is conventional paper rather than the special paper having increased smoothness of surface. The conventional paper has irregularities ranging through various degrees since it is made of interlocking fibers. Thus, fused ink cannot penetrate into the fibers of the paper and is deposited only on or near the raised portions of the surface. The resulting image would have dull edges or incomplete parts. In order to improve the quality of print, a hotmelt binder having a lower melting point may be used. However, it may be disadvantageous in that the thermally transferable ink layer is adhesive even at relatively low temperatures, resulting in degradation of the shelf stability and contamination of unprinted sheet parts.
In the thermal transfer type recording process, the thermal transfer medium is in contact with the recording sheet under pressure from a recording head. The thermal transfer medium is separated from the recording sheet at the end of the recording head. The time required to separate the thermal transfer medium from the recording sheet after the ink layer is thermally applied to the recording sheet is very short. Therefore, the thermal transfer medium must be separated from the recording sheet before the fused ink is solidified. As a result, the ink would not fully be transferred to the recording sheet.